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Betel System
Betelgeuse, also known by its Bayer designation: Alpha Orionis (α Orionis, α Ori), is the second largest star in the Orion Arm and one of the largest in the Milky Way. Classified as a red supergiant, Betelgeuse is one of the largest and most luminous stars known. If it were at the center of, for example, the Sol System, its surface would extend past the asteroid belt, possibly to the orbit of Jupiter and beyond, wholly engulfing the four inner planets. Betelgeuse currently lies 25,440 ly from the core. In 1920, Alpha Ori was the first star by humans (after Sol) to have its angular diameter measured. Since then, human researchers have used a number of telescopes to measure this stellar giant, each with different technical parameters, often yielding conflicting results. Betelgeuse has a complex, asymmetric envelope caused by colossal loss of mass involving huge plumes of gas being expelled from its surface. There is even evidence of some stellar companions orbiting within this gaseous envelope, possibly contributing to the star's eccentric behavior. Astronomers believe Betelgeuse is only 10 million years old, but has evolved rapidly because of its high mass. Currently in the late stage of its evolution, Betelgeuse is expected to explode as a supernova possibly within the next million years. Properties Betelgeuse's spectral type is listed as M2Iab in the Simbad astronomical database, signifying that it is a red star. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. The "ab" suffix is derived from the Yerkes spectral classification system, and indicates that it is an intermediate luminous supergiant, less bright than other supergiants like Dene. However, given some of the recent findings, this classification may be outdated, as there is evidence Betelgeuse is actually much more luminous than Deneb and other stars in its class. Assuming an average radius of 5.5 AU and a diameter of 1.6 billion km, theoretical calculations would yield a luminosity figure in excess of 180,000 Sols (L) at maximum. When the star contracts as it appears to have since 1993, its luminosity would diminish to about 130,000L. Either way, that amount of electromagnetic energy dwarfs Deneb's output of about 50,000L☉. But with most of the star's radiant energy occurring in the infrared and huge amounts being absorbed by circumstellar matter, the human eye simply cannot perceive the star's intrinsic brightness. Given the many uncertainties surrounding Betelgeuse, no consensus has yet emerged regarding the star's mass. Estimates range from 5 to 30 Sols (M☉) with most investigators showing a preference for a relatively large mass ranging from 10 to 20M☉. One model reports a mass at the lower end of the scale at 14M☉, although a mass ranging from 18 to 20 is more commonplace. Typical of red supergiants, Betelgeuse is a cool star with surface temperatures reported between 3,500 to 3,600K. It is also a slow rotator, with the most recent velocity recorded at 5 km/s.Depending on its photospheric radius, it could take the star anywhere from 25 to 32 years to turn on its axis—extremely slow when compared with a fast rotator like Pleione in the Pleiades, which turns on its axis once every 11.8 hours. In 2002, astronomers using sophisticated computer simulations began to speculate that Betelgeuse might exhibit magnetic activity in its extended atmosphere, a factor where even moderately strong fields could have a meaningful influence over the star's dust, wind and mass-loss properties. Life cycle The future fate of Betelgeuse depends on its mass—a critical factor which is not well understood. Since most investigators concede a mass greater than 10 Sols, the most likely scenario is that the supergiant will continue to burn and fuse elements until its core is iron, at which point Betelgeuse will explode as a type II supernova. During this event the core will collapse, leaving behind a neutron star remnant some 20 km in diameter. Betelgeuse is already old for its size class and is expected to explode relatively soon compared to its age. Solving the riddle of mass-loss will be the key to knowing when a supernova may occur, an event expected anytime in the next million years. Supporting this hypothesis are a number of unusual features that have been observed in the interstellar medium of the Rigel Sector which suggest that there have been multiple supernova explosions in the recent past. Betelgeuse's suspected birthplace in the OB1 Association is the probable location for such supernovae. Since the oldest subgroup in the association has an approximate age of 12 million years, the more massive stars likely had sufficient time to evolve to this stage. Also, because runaway stars are believed to be caused by supernova explosions, there is strong evidence that OB stars all originated with such an explosion. Category:Orion Arm Category:Rigel Sector Category:Systems Category:Mining communities Category:M2-type stars Category:Supergiant stars